Optimize Smi keys for KeyedLoads

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1855 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(JSArrayLength)
 
  protected:
   virtual bool DataEquals(HValue* other_raw) { return true; }
 };
 
 
 class HFixedArrayBaseLength: public HUnaryOperation {
  public:
   explicit HFixedArrayBaseLength(HValue* value) : HUnaryOperation(value) {
+    set_type(HType::Smi());
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetGVNFlag(kDependsOnArrayLengths);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(FixedArrayBaseLength)
@@ skipping 849 matching lines @@
   HValue* arguments() { return OperandAt(0); }
   HValue* length() { return OperandAt(1); }
   HValue* index() { return OperandAt(2); }
 
   DECLARE_CONCRETE_INSTRUCTION(AccessArgumentsAt)
 
   virtual bool DataEquals(HValue* other) { return true; }
 };
 
 
+enum BoundsCheckKeyMode {
+  DONT_ALLOW_SMI_KEY,
+  ALLOW_SMI_KEY
+};
+
+
 class HBoundsCheck: public HTemplateInstruction<2> {
  public:
-  HBoundsCheck(HValue* index, HValue* length) {
+  HBoundsCheck(HValue* index, HValue* length,
+               BoundsCheckKeyMode key_mode = DONT_ALLOW_SMI_KEY)
+      : key_mode_(key_mode) {
     SetOperandAt(0, index);
     SetOperandAt(1, length);
     set_representation(Representation::Integer32());
     SetFlag(kUseGVN);
   }
 
-  virtual Representation RequiredInputRepresentation(int index) {
-    return Representation::Integer32();
+  virtual Representation RequiredInputRepresentation(int arg_index) {
+    if (index()->representation().IsTagged() &&
+        !index()->IsConstant() &&
+        key_mode_ == ALLOW_SMI_KEY) {
+      return Representation::Tagged();
+    } else {
+      return Representation::Integer32();
+    }
   }
 
   virtual void PrintDataTo(StringStream* stream);
 
   HValue* index() { return OperandAt(0); }
   HValue* length() { return OperandAt(1); }
 
   DECLARE_CONCRETE_INSTRUCTION(BoundsCheck)
 
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
+  BoundsCheckKeyMode key_mode_;
 };
 
 
 class HBitwiseBinaryOperation: public HBinaryOperation {
  public:
   HBitwiseBinaryOperation(HValue* context, HValue* left, HValue* right)
       : HBinaryOperation(context, left, right) {
     set_representation(Representation::Tagged());
     SetFlag(kFlexibleRepresentation);
     SetAllSideEffects();
@@ skipping 2368 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(LoadFieldByIndex);
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_